Remember the post about eliminating glucagon curing diabetic mice? Here is a possible explanation of the fact that they were able to survive without insulin:
Also, we support prior data reporting that obese nondiabetic humans increase β-cell mass, presumably in response to insulin resistance (8,9). However, the extent of this increase (∼50%) in the markedly obese humans studied here is much lower than the increase observed in obese mice (5- to 10-fold) (34).
I got it from this paper:
This would seem to imply that the mice in the study did start to produce insulin again, because they can grow new islet cells very rapidly and well. Another reason I think that study was garbage!